Laserfiche WebLink
i <br /> I 15 February 1999 <br /> AGE-NC Project No 96-0229 <br /> Page 8 of 9 <br /> • Laboratory data indicates that the greatest concentrations of TPH-g impacted ground water <br /> I are located near MW-1, MW-2, MW-3 and MW-6 The approximate known extent of <br /> dissolved TPH-g is depicted in Figure 11 <br /> • Benzene was detected to samples collected from wells MWA, MW-3,MW-4, MW-6, MW- <br /> 7, MW-10A and MW-10B at concentrations above the State of California Maximum <br /> Contaminant Level (MCL) for drinking water of 10 ppb The area with the highest <br /> concentrations of dissolved benzene is located near the area of MW-1 and MW-6 <br /> • Concentrations of toluene were above the MCL of 150 ppb in wells MW-1, MW-2, MW-3 <br /> and MW-6 <br /> C Concentrations of ethylbenzene were above its MCL of 700 ppb In wells MW-1, MW-2 and <br /> MW-6 <br /> • Concentrations of xylenes were above the MCL of 1,750 ppb in wells MW-1,MW-2, MW-3 <br /> and MW-6 <br /> r • Utilizing EPA methods 8020 and 8260, concentrations of MTBE were detected above the <br /> laboratory reporting limits in samples from wells MW-1, MW-4, MW-6, MW-7, MW-8 <br /> MW-l0A and MW-IOB <br /> o From May 1998 to October 1998, substantial increasing dissolved concentrations of <br /> petroleum hydrocarbons were reported from MW-1, MW-3 and MW-6 (Table 3) The <br /> substantial increases could be attributed to a shift of the dissolved petroleum hydrocarbon <br /> core-area towards the northeast <br /> I • Laboratory data suggest that the dissolved total petroleum hydrocarbon plume beneath the <br /> site appears to have taken a relatively elongated oval shape oriented towards the northeast <br /> (Figure 12), laboratory data suggest that the dissolved MTBE plume beneath the site appears <br /> Ito have taken a relatively elongated oval shape oriented towards the north <br /> 5.0. RECOMMENDATIONS <br /> Based upon data collected during October 1998, AGE recommends <br /> • Installation of additional ground water monitoring well northeast of the site (downgradient) <br /> in order to assess the full extent of off-site dissolved petroleum hydrocarbons <br /> • Continued quarterly ground water monrtonng and sampling should be performed at the site <br /> in January 1999 <br /> • Arrangements should be made to dispose of stockpiled soil at the site by hauling off-site to <br /> Advanced GeoEn►ironmental,Inc <br />